Liquid fuel compositions



1 apart" United States Patent 2,917,378 LIQUID FUEL COMPOSITIONS Emil A. Vitalis, Springdale, and Frederick L. Andrew, Glenbrook, Conn., assignors to American Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Application December 8, 1955 Serial No. 551,719

12 Claims. (Cl. 52 .5)

The present invention relates to liquid fuel compositions having improved low temperature characteristics and more specifically is concerned with compositions containing kerosene, gasoline, diesel and turbo-jet fuels having lower freezing points and wherein the formation of ice crystals is prevented until lower temperatures are reached.

Petroleum hydrocarbons have been established as the presently preferred fuels for spark-ignition engines, compression-ignition engines and jet-propulsion engines, the latter including the gas-turbine type of power plant, particularly employed for aircraft propulsion purposes. As used herein, these petroleum hydrocarbons fall into several loosely-defined classes of which the following are pertinent to the present invention: (1) aviation gasoline, the petroleum fraction boiling between about 100 and about 330 F.; (2) motor gasoline, the petroleum fraction boiling between about 100 F. and about 430 F.; (3) kerosene and diesel fuel, the fraction boiling between about 300 and about 625 F., and (4) jet fuel,

the fraction boiling between about 100 and about 600 F. and preferably between about 1 -50 and about 550 F. All these products may be made up of straight run, thermally cracked and/or catalytically cracked components. With particular reference to kerosene and jet fuels which will be employed as illustrative but not limitative of the present invention, such products possess desirable characteristics of fire safety, engine power requirements, freezing points, flash points, vapor loss, cost and availability which have rendered them mostsuitable for the fuel for jet aircraft. 7 7

Aviation kerosene is a blend of petroleum fractions and is made to meet a variety of specifications. The following data are presented to illustrate one particular commercial product:

Distillation (20% evap.) 392 F. max.

End point 572 F. max. Residue, percent v. 2.0 max. Loss, percent 1.5 max. Sulfur, percent w. max. 0.2.

Freezing point 40 F. B.t.u./lb. net, min. 18,300.

Flash point 100 F.

Similarly, turbo-jet fuels are blends of petroleum fractions and are made to meet a variety of specifications. The following data are presented to illustrate one particular product, namely, JP-4, which is a wide-cut petroleum fraction covering the boiling point range of both gasolines and diesel fuels:

Flash point 10 F.

Low temperature characteristics, ice crystal formation and freezing points of liquid fuels, and particularly jet fuels, are important factors leading to the acceptance thereof and this is especially so in military service and cold weather operations wherein the requirements are rigorous and varied. For example, the Mil- F-5624B specification sets forth a -76" F. maximum limit freeze point and this factor has drastically reduced the availability of acceptable products for military purposes and concomitantly increased the cost thereof.

This low freezing point value has been required in order to provide maximum pumpability of the liquid fuel in the aircraft or like fuel systems under extremely frigid conditions or at very high altitudes and to avoid the formation of ice crystals in the fuel whereby its low temperature behavior is seriously affected. At certain temperatures, fuels may contain up to 0.015 percent by weight of water dissolved in the fuel which, as the fuel temperature is reduced and its water solubility decreased, could lead to the separation of water and the undesirable formation of ice crystals. The possibility of blockages, such as in fuel filters, carburetors, and other operational equipment, is created with resulting engine failures and accident-ridden flight conditions.

it is a purpose of the present invention to provide for liquid fuel compositions, and particularly jet fuel compositions, with lower freezing points than those currently used and wherein ice formation is considerably retarded until lower temperatures are reached.

We have added many compounds to fuels in efforts to improve their operating characteristics and properties. For example, dioctyl sodium sulfosuccinate (hereinafter called A-OT), dihexyl sodium sulfosuccinate, (hereinafter called A-MA) and guanidine tallate have been added individually to fuels in amounts up to about 1% by weight but no unusual depression of freezing points or improved low temperature performance was noted. Similarly, when methanol, ethanol, Z-rnethoxy ethanol, (methyl Cellosolve), 2-ethoxy ethanol (ethyl Cellosolve), Z-butoxy ethanol (butyl Cellosolve), propanol, isopropanol and butanol were added individually in amounts up to 1% by weight to liquid fuels, no unusual depression of freezing points or improvement in low temperature characteristics was noted.

It has now been surprisingly found that mixtures of certain surface active agents and alcohols are capable of lowering the freezing points of the above-described fuels or lowering the temperature at which ice crystals first appear by addition thereto in very small aruounts, sufficient to improve these low temperature characteristics.

Amounts as low as about 0.01% by weight of the mixtures have been observed as exerting an effect on the low temperature performance characteristics, with amounts up to as high as 5% by weight being found utilizable. Within the more commercial aspects of the present invention, from about 0.1 to about 3% by weight has been found preferable. These percentages are to be noted as based on the weight of the liquid fuel composition.

The standard test used to evaluate the effect on the low temperature characteristics and properties of fuels is as follows: The surface active agent and the alcohol were added individually or jointly to the selected fuel in the percentage by weight as indicated in the tables. The liquid fuel was then slowly cooled with constant stirring 'to avoid local temperature effects and was observed very closely during the cooling for the development of cloudiness or haziness, the appearance of minute ice crystals, and its ultimate solidification or freezing. The procedure was then reversed and the fuel allowed to warm slowly and observations taken as to remelting of the frozen fuel and the disappearance of cloudiness, haziness and minute ice crystals. All tests were run at standard atmospheric pressure. All temperatures, unless indicated otherwise,'are Fahrenheit.

Table 1 illustrates the lack of effect of surface active agents and lower aliphatic alcohols on a commercial grade of kerosene suitable as a turbo-jet fuel and possessing the indicated low temperature characteristics and properties.

Table 2 illustrates the synergistic effect of the mixture of thecombined surface active agents and alcohols on the low temperature properties and characteristics of a commerieal grade of kerosene (similar to that of Table 1) a suitable as a turbo-jet fuel:

Table 2 Ice Cloud Freeze Ice Crys- Crystals Point Point tals Disppear appear Klero syeris golntrol, N o additive..- 37 50 -65 +32 0. 25 83 il 55 -80 80 -25 ...5 guani inc ta at 0.257: 2-butoxy ethanoL. 57 80 80 40 Table 3 illustrates the synergistic effect of various combinations of surface active agents and alcohols on another grade of kerosene:

Table 3 Cloud Ice Crysloint tals DIS- appear Kerosene Control, N o additive +20 +32 0.25% A-OT +20 +32 0 25% ethanol +20 +32 0 25% isopropanol. +20 +32 0.25% guanidlne tallate +20 +32 0.25% 2-rnethosy etlmnoL- +2 +32 0.25% 2 ethoxy etlmnol- +20 +32 0.125 OT 40 0.375% Isopropanol. 0.25 -o'r Isopropanol 30 Isogrgphhhl. l 20 +20 my: homes-11:: 0.25% OT l 8%? 5'03" I 30 0592 Efhanfsl 0 1% -40 30 fsg r t Tl'i guani me a a e 2-0tl10ly ethzlilnoli 0 guani ine ta ate" 0.25%; 2-methow ethanol l 30 +10 1% guanidine tallate... 5 1% 2-butoxy ethanol.-.

Table 4 illustrates the synergistic effect of other combinations of surface active agents and alcohols on another grade of kerosene having a cloud point and ice crystal disappearance temperature as indicated:

Table 4 Cloud Ice Crys- Point tals Disappear Kerosene Control, No additive 50 +32 0.2% auanidine tallate 50 +32 +32 0.40% 2-butoxy ethanol.-.

A similar test was run on turbine fuel JP-S having distillation specifications of 400 F. for 10% evaporation and 500 F. end point, a fiash point of 140 F. and a freeze point of 40 F. 0.125 grams of A-OT and 0.375 gram of ethyl alcohol were added to a 100 gram sample of the fuel and the temperature of the composition was slowly lowered with constant stirring. At 40 F., the normal freeze point of the fuel, the protected sample had not gelled and was not frozen.

Another test was run on turbine fuel JP-4 (a wide-cut fuel corresponding roughly to a mixture of about 65% low octane gasoline fractions and about 35% kerosene) having distillation specification of 270 F. for 20% evaporation, 370 F. for 50% evaporation and 470 F. for evaporation, a fiash point of 10 F. and a freeze point of 76 F. 0.2 gram of A-OT and 0.4 gram of ethyl alcohol were added to a gram sample of the fuel and its temperatures slowly lowered with constant stirring. At 76 F., the fuel composition had not gelled and was not frozen.

Another sample of turbine fuel JP-4, per se, was selected and was slowly cooled to observe the physical changes in its appearance. At 20 F., the fuel became cloudy; at 60 F., the fuel became very turbid; at 70" F., it became viscous and at 98 F., it gelled. The procedure was then reversed and the fuel was permitted to gradually warm. At 60 F., the fuel became turbid; at 58 F., it became hazy and did not clear up until +20 F.

To another portion of JP-4 fuel (referred to in the preceding paragraph), 0.0625% by weight of A-OT and 0.1875 by weight of ethyl alcohol was added. The jet fuel composition was then cooled and did not cloud until -60 F. and did not become turbid until 62 F. The fuel gelled at about 98" F. and, when the procedure was reversed, it cleared up very quickly and was clear at approximately 60 F.

To another portion of TP-4 fuel (referred to in the preceding two paragraphs) was added 0.1% by weight of guanidine tallate and 0.15% by weight of butyl Cellosolve. The inhibited composition did not cloud until about 60 F. and did not become turbid until 62 F. The fuel gelled at 98 F. and, when the procedure was reversed, it cleared up very quickly and was clear at 60" F.

It is, of course, to be appreciated that, although the invention has been described primarily with reference to aviation fuels and particularly turbojet fuels, such has been the case essentially for purposes of illustration and should not be construed as limitative of the invention. The low temperature characteristic improvements are of established utility in other power plant fuels such as used in diesel and gasoline internal combustion engines.

The invention would therefore find applicability in power fuels specifically such as aviation gasoline, motor gasoline and power kerosene for spark-ignition engines; automotive diesel fuel for compression-ignition engines and jet fuels for jet propulsion engines.

Although we have described specific examples of our inventive concept, we consider the broad aspects of the same not to be limited to the specific substances mentioned therein but to include various other compounds of equivalent function and constitution as set forth in the claims appended hereto. It is understood that any suitable changes, modifications, and variations may be made without departing from the spirit and scope of the invention.

We claim:

1. A liquid fuel consisting essentially of a petroleum fraction boiling between about 100 F. and about 625 F. and, as a low temperature characteristic improver therefor, from about 0.01% to about 5% by weight of a member of the group consisting of (a) from about 1 to about 4 parts by weight of dioctyl sodium sulfosuccinate together with from about 1 to about 4 parts by weight of a saturated aliphatic alcohol containing from 2 to 3 carbon atoms and (b) from about 1 to about 2 parts by weight of guanidine tallate together with from about 1 to about 2 parts by weight of a 2-alkoxy ethanol wherein the alkoxy group contains up to 4 carbon atoms.

2. A low temperature characteristic irnprover for liquid fuels consisting essentially of a petroleum fraction boiling between about 100 F. and about 625 F., said improver being a mixture of from about 1 to about 2 parts by weight of guanidine tallate and from about 1 to about 2 parts by weight of a Z-alkoxy ethanol wherein the alkoxy group contains up to 4 carbon atoms.

3. A low temperature characteristic improver for liquid fuels as defined in claim 2 wherein the alkoxy group is butoxy.

4. A low temperature characteristic improver for liquid fuels as defined in claim 2 wherein the alkoxy group is ethoxy.

5. A low temperature characteristic improver for liquid fuels as defined in claim 2 wherein the alkoxy group is methoxy.

6. A liquid fuel consisting essentially of a petroleum fraction boiling between about F. and about 625 F. and, as a low temperature characteristic improver, from about 0.01% to about 5% by weight of a mixture of from about 1 to about 4 parts by weight of dioctyl sodium sulfosuccinate and from about 1 to about 4 parts by weight of a saturated aliphatic alcohol containing from 2 to 3 carbon atoms.

7. A liquid fuel as defined in claim 6 wherein the aliphatic alcohol is ethanol.

8. A liquid fuel as defined in claim 6 wherein the aliphatic alcohol is isopropanol.

9. A liquid fuel consisting essentially of a petroleum fraction boiling between about 100 F. and about 625 F. and, as a low temperature characteristic improver, from about 0.01% to about 5% by weight of a mixture of from about 1 to about 2 parts by weight of guanidine tallate and from about 1 to about 2 parts by weight of a 2-alkoxy ethanol wherein the alkoxy group contains up to 4 carbon atoms.

10. A liquid fuel as defined in claim 9 wherein the alkoxy group is butoxy.

11. A liquid fuel as defined in claim 9 wherein the alkoxy group is ethoxy.

12. A liquid fuel as defined in claim 9 wherein the alkoxy group is methoxy.

References Cited in the file of this patent UNITED STATES PATENTS 2,461,797 Zwicky Feb. 15, 1949 2,550,982 Eberz May 1, 1951 2,579,692 Neudeck Dec. 25, 1951 2,599,338 Lifson et a1 June 3, 1952 2,850,368 Vanderbilt et al Sept. 2, 1958 

1. A LIQUID FUEL CONSISTING OF ESSENTIALLY OF A PETROLEUM FRACTION BOILING BETWEEN ABOUT 100*F. AND ABOUT 625*F. AND, AS A LOW TEMPERATURE CHARACTERISTIC IMPROVER THEREFOR, FROM ABOUT 0.01% TO ABOUT 5% BY WEIGHT OF A MEMBER OF THE GROUP CONSISTING OF (A) FROM ABOUT 1 TO ABOUT 4 PARTS BY WEIGHT OF DIOCTYL SODIUM SULFOSUCCINATE TOGETHER WITH FROM ABOUT 1 TO ABOUT 4 PARTS BY WEIGHT OF A SATURATED ALIPHATIC ALCOHOL CONTAINING FROM 2 TO 3 CARBON ATOMS AND (B) FROM ABOUT 1 TO ABOUT 2 PARTS BY WEIGHT OF GUANIDINE TALLATE TOGETHER WITH FROM BOUT 1 TO ABOUT 2 PARTS BY WEIGHT OF A 2-ALKOXY ETHANOL WHEREIN THE ALKOXY GROUP CONTAINS UP TO 4 CARBON ATOMS. 